How did *Wiwaxia*'s dermal armor contrast with the exoskeleton strategy of the arthropod *Sidneyia*?

Arthropods like Sidneyia developed articulated exoskeletons made of chitin and mineralized plates, unlike Wiwaxia's scale-like dermal protection.

Comparing *Wiwaxia* to contemporaneous arthropods like *Sidneyia* highlights distinct evolutionary solutions to the problem of defense during the Cambrian. Arthropods evolved complex, articulated external skeletons, or exoskeletons, constructed from chitin reinforced with mineralized plates. This system was intrinsically linked to growth via periodic molting. Conversely, *Wiwaxia*'s defense relied on a system more analogous to dispersed dermal bone or scales, integrated into a soft-bodied form. This contrast between *Wiwaxia*'s separate, interlocking armor pieces and the unified, jointed carapace of early arthropods illustrates the simultaneous, varied nature of armor evolution occurring as selection pressures began to filter body designs.